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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 920 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  2. 2.√48 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 6.8 (d) 7.0
  3. 3.√27 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.3 (d) 5.4
  4. 4.Best estimate of 1564 ÷ 68? (a) 2200 (b) 220 (c) 22
  5. 5.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.2
  6. 6.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.0 (d) 6.2
  7. 7.√69 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.1 (d) 8.2
  8. 8.Best estimate of 4369 ÷ 46? (a) 870 (b) 87 (c) 8700
  9. 9.Best estimate of 1807 ÷ 29? (a) 600 (b) 6000 (c) 60
  10. 10.Best estimate of 1769 ÷ 78? (a) 220 (b) 2200 (c) 22
  11. 11.Best estimate of 4224 ÷ 66? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 3144 ÷ 37? (a) 790 (b) 7900 (c) 79
  13. 13.√70 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.4 (d) 8.3
  14. 14.Best estimate of 3932 ÷ 51? (a) 7900 (b) 790 (c) 79
  15. 15.Best estimate of 2407 ÷ 28? (a) 8000 (b) 80 (c) 800
  16. 16.Best estimate of 4481 ÷ 53? (a) 900 (b) 9000 (c) 90
  17. 17.Best estimate of 4173 ÷ 68? (a) 600 (b) 60 (c) 6000
  18. 18.√67 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 8.3 (d) 8.1
  19. 19.Best estimate of 1067 ÷ 24? (a) 53 (b) 5300 (c) 530
  20. 20.√22 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.8 (d) 4.7
  21. 21.Best estimate of 902 ÷ 24? (a) 450 (b) 45 (c) 4500
  22. 22.Best estimate of 701 ÷ 54? (a) 14 (b) 1400 (c) 140
  23. 23.Best estimate of 3524 ÷ 72? (a) 500 (b) 5000 (c) 50
  24. 24.Best estimate of 2629 ÷ 88? (a) 290 (b) 2900 (c) 29
  25. 25.√46 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  26. 26.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 5.6
  27. 27.Best estimate of 7557 ÷ 83? (a) 9400 (b) 940 (c) 94
  28. 28.Best estimate of 1214 ÷ 48? (a) 24 (b) 240 (c) 2400
  29. 29.√31 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.6 (d) 5.7
  30. 30.Best estimate of 3551 ÷ 38? (a) 89 (b) 8900 (c) 890
  31. 31.Best estimate of 7584 ÷ 87? (a) 840 (b) 8400 (c) 84
  32. 32.Best estimate of 1372 ÷ 36? (a) 3400 (b) 34 (c) 340
  33. 33.Best estimate of 1698 ÷ 61? (a) 280 (b) 28 (c) 2800
  34. 34.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  35. 35.Best estimate of 3236 ÷ 52? (a) 65 (b) 6500 (c) 650
  36. 36.Best estimate of 4621 ÷ 58? (a) 77 (b) 770 (c) 7700
  37. 37.Best estimate of 2118 ÷ 73? (a) 3000 (b) 300 (c) 30
  38. 38.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 8.9
  39. 39.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.5
  40. 40.Best estimate of 2386 ÷ 49? (a) 48 (b) 4800 (c) 480

Answer key

  1. 6.4
  2. 6.9
  3. 5.2
  4. 22
  5. 7.4
  6. 6.3
  7. 8.3
  8. 87
  9. 60
  10. 22
  11. 60
  12. 79
  13. 8.4
  14. 79
  15. 80
  16. 90
  17. 60
  18. 8.2
  19. 53
  20. 4.7
  21. 45
  22. 14
  23. 50
  24. 29
  25. 6.8
  26. 5.8
  27. 94
  28. 24
  29. 5.6
  30. 89
  31. 84
  32. 34
  33. 28
  34. 9.9
  35. 65
  36. 77
  37. 30
  38. 9.1
  39. 7.6
  40. 48

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